Conventionally, a fibrous casing for packaging a processed meat product such as ham and sausage has been known. As such a fibrous casing, a fibrous casing provided with an inner layer comprising pulp as a principal component and an outer layer overlaid on an outer face side of the inner layer has been known. Such a fibrous casing having the inner layer and the outer layer is able to retain a food modifier such as a smoke solution, a seasoning, a colorant, a preservative and the like in the inner layer, and to transfer these components to a filling during cooking and the like.
As such a fibrous casing having an inner layer and an outer layer, for example, a packaging material comprising paper (inner layer) and a heat-sealable nonwoven fabric (outer layer) being laminated has been proposed (refer to Japanese Unexamined Patent Application, Publication No. H6-312494). The packaging material is formed by layering the paper and the nonwoven fabric and then impregnating them with a viscose solution. In such a packaging material, the viscose solution is able not only to bond the paper with the nonwoven fabric, but also to coat the paper, whereby peelability of the paper from the filling is improved.
However, such a conventional fibrous casing which employs the viscose solution as described above is costly and requires a complex production procedure.
In light of suppression of cost and simplification of the production steps, it may be contemplated not to employ the viscose solution. However, in the conventional fibrous casing, vinylon-added rayon paper or chemical fiber-blended paper are used as the paper. Therefore, in the case of these types of paper not being coated by viscose, vinylon may leak out from the rayon paper upon heating and attach to the filling. In the case of the chemical fiber-blended paper, a binder fiber may be fused and leak upon heating and attach to the filling. Furthermore, employing paper in the inner layer may cause inconveniences such as uneven transfer of the food modifier to a foodstuff and inferior adhesiveness between the inner layer (paper layer) and the outer layer (synthetic resin layer) leading to interlayer delamination during use.
Moreover, fibrous casing is required: to retain a sufficient amount of the food modifier within the inner layer; to have a function of efficiently transferring, i.e., releasing the food modifier toward a packaged foodstuff; to be superior in peelablility from the filling; not to attach a minute unwanted substance derived from the inner layer onto the filling; and the like. However, in the case of employing normal paper in the inner layer, liquid retention and releaseabilty, peelability from the filling, prevention of the minute unwanted substance derived from the inner layer from attaching onto the filling, and the like are insufficient. Given the above, a fibrous casing which is superior in these performances is desired to be developed.